Hip flexor muscles

Description

The hip flexors are body wall muscles of the pelvic region that have been annexed by the lower limb during development. These muscles, the psoas major and iliacus, gain tremendous mechanical advantage as they pass over the superior ramus of the pubis on their descent onto the femur. This pulley-like arrangement of the muscles orients the force vector of the common iliopsoas tendon at approximately ninety degrees to its attachment on the femur throughout the full range of motion. This optimization of the mechanical advantage allows these muscles to be powerful flexors of the hip joint.